UNIVERSITY  OF  CALIFORNIA 

COLLEGE    OF    AGRICULTURE 

AGRICULTURAL    EXPERIMENT    STATION 

BERKELEY,    CALIFORNIA 

CIRCULAR  300 
December,  1925 

COCCIDIOSIS  OF  CHICKENS 

J.  K.  BEACH  and  D.  E.  DAVIS* 


Coccidiosis  is  one  of  the  most  destructive  diseases  of  young 
chickens.  It  is  so  widespread  that,  in  poultry  districts,  practically 
all  established  poultry  farms  are  infected  and  new  farms  quickly 
become  so.  The  heaviest  losses  occur  in  chicks  from  four  to  eight 
weeks  old.  In  infected  flocks  from  25  to  50  per  cent  and  sometimes 
nearly  all  of  the  chicks  die  in  two  or  three  weeks.  The  large  number 
of  unthrifty  or  "cull"  chicks  among  the  survivors  in  infected  flocks 
that  have  not  been  given  effective  treatment  sometimes  causes  a 
greater  loss  to  the  poultryman  than  the  mortality.  Older  birds 
become  affected  with  a  slowly  fatal  (chronic)  type  of  the  disease, 
which  may  be  general  in  the  flock  or,  as  frequently  happens,  affect 
only  a  few  birds.  The  disease  frequently  occurs  in  young  turkeys 
as  well  as  in  chickens. 

CAUSED    BY  A   PARASITE 

Coccidiosis  is  caused  by  the  presence  in  the  intestines  of  chicks  of 
a  microscopic,  protozoan  parasite  called  Eimeria  avium.  The  parasite 
develops  and  multiplies  in  the  cells  of  the  walls  of  the  intestines.  The 
disease  results  from  the  injury  to  the  cells  during  this  period  of 
development.  In  young  chicks,  the  ceca  (blind  pouches)  are  the 
parts  affected,  while  in  older  birds  with  the  chronic  type  of  the 
disease,  the  small  intestines,  rather  than  the  ceca,  are  involved. 

Severe  outbreaks  of  coccidiosis  so  frequently  occur  in  flocks  which 
have  not  received  suitable  food  or  care  or  which  are  not  properly 
housed,  that  some  poultrymen  believe  it  to  be  due  to  such  conditions. 
These  conditions  do  not  cause  coccidiosis,  but  render  them  more  sus- 
ceptible by  lowering  their  natural  resistance.  Therefore,  such  things 
as  over-feeding,  sudden  changes  in  the  ration,  poorly  ventilated 
houses,  raising  too  many  chicks  in  a  house,  failure  to  keep  the  houses 
warm  and  dry  day  and  night  and  especially  during  cold,  rainy 
weather,  and  failure  to  keep  the  houses  clean  favor  the  occurrence 
of  serious  outbreaks. 


*  Division  of  Veterinary  Science. 


UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 


CIRC.  300]  COCCIDIOSIS   OF    CHICKENS 


LIFE     CYCLE     OF    THE     PARASITE 

In  the  completion  of  its  life  cycle,  the  parasite  -  passes  through 
many  forms  or  stages  of  development.  A  knowledge  of  certain  of 
these  stages  is  of  practical  importance  in  the  application  of  effective 
preventive  and  control  measures. 

The  first  stage,  or  egg  stage,  of  the  parasite  is  known  as  an 
oocyst  (fig.  1,  A).  Large  numbers  of  oocysts  are  present  in  the  drop- 
pings of  affected  chicks.  Oocysts  in  freshly  expelled  droppings  are  not 
harmful  when  taken  into  the  intestines  of  chicks.  Under  the  conditions 
of  moisture  and  temperature  such  as  are  found  in  brooder  houses,  how- 
ever, in  two  or  three  days  they  undergo  a  change  known  as  sporulation. 

(%  1,  B.) 

In  the  brooder  yards,  conditions  are  less  favorable  for  sporulation 
and  a  longer  time  is  required  for  it  to  take  place.  It  is  the  sporulated 
oocyst  which  causes  coccidiosis  when  ingested  by  susceptible  chicks. 
This  form  is  very  resistant  and  may  remain  alive  in  the  soil  of  poultry 
yards  for  a  year  or  longer.  When  the  sporulated  oocysts  are  taken 
into  the  intestine,  very  minute,  motile  forms,  known  as  sporozoites, 
(fig.  1,  C),  are  released.  These  penetrate  the  cells  of  the  mucous 
membrane  lining  of  the  ceca  or  small  intestines.  There  they  develop 
and  multiply  by  what  is  known  as  the  asexual  cycle.  The  final  stage 
of  this  developmental  is  called  a  merozoite  (fig.  1,  C).  The  merozoites 
migrate  to  other  cells  and  either  pass  through  an  asexual  cycle,  like 
the  sporozoites,  or  through  what  is  known  as  the  sexual  cycle,  the  final 
stage  of  which  is  the  oocyst  (egg  stage).  The  oocysts  do  not  develop 
further  in  the  intestines  of  the  birds,  but  pass  out  with  the  droppings 
and  undergo  sporulation  as  previously  described.  The  development 
and  multiplication  of  the  parasite  in  the  walls  of  the  ceca  and  intes- 
tines cause  extensive  destruction  of  the  mucous  membrane  lining. 
Often  also  the  walls  of  small  blood  vessels  are  destroyed.  This  results 
in  hemorrhage  into  the  ceca  and  the  appearance  of  blood  in  the 
droppings. 

CONTAMINATED    SOIL    COMMON    SOURCE    OF    INFECTION 

Chickens  become  infected  with  coccidiosis  by  the  ingestion  of  food 
or  drinking  water  contaminated  with  sporulated  oocysts.  The  soil  of 
yards  in  which  infected  chickens  have  been  kept  is  the  most  common 
source  of  the  infection.  Brooder  houses,  feeding  and  watering  vessels, 
hovers  and  other  accessories  previously  used  for  infected  birds  and 
which  have  not  been  property  cleaned  may  be  a  source  of  the  infection. 


4  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

Attendants  may  carry  infection  into  brooder  houses  from  contami- 
nated yards.  Chicks  may  become  infected  when  allowed  to  run  in 
orchards  or  gardens  that  have  been  fertilized  with  chicken  manure. 
The  infection  may  be  introduced  on  to  new  premises  by  such  means  as 
healthy  adult  fowls  which  harbor  the  germs,  wild  birds,  dust -laden 
wind,  visitors,  etc.  It  is  improbable  that  infected  hens  ever  transmit 
the  disease  through  the  egg  to  their  offspring. 


Fig.  2.  Cliick  with  coccidiosis. 
DROOPINESS   FIRST  SYMPTOM    IN   CHICKS 

Usually  the  first  indication  of  the  presence  of  coccidiosis  in  a 
flock  of  chicks  is  droopiness  of  a  few.  The  affected  birds  remain  close 
to  the  hover,  do  not  eat,  and  stand  with  wings  drooping,  head  drawn 
in,  and  eyes  closed  for  long  periods  of  time  unless  disturbed.  This 
attitude  is  quite  characteristic  of  the  disease  (fig.  2).  Droopy  birds 
may  be  seen  for  two  or  three  days  before  any  deaths  occur. 

BLOODY    DIARRHEA    NOT    ALWAYS    PRESENT 

The  droppings  of  affected  chicks  frequently  contain  blood.  The 
amount  varies  from  that  sufficient  only  to  slightly  tinge  the  droppings 
to  enough  to  give  them  the  appearance  of  consisting  entirely  of  blood. 
The  bloody  droppings  usually  are  seen  in  the  early  stages  of  the  out- 
break.    Occasionally  they  are  the  first  indication  of  disease  observed. 

Although  the  presence  of  blood  in  the  droppings  is  a  frequently 
occurring   and   quite   characteristic   symptom,   it   must   be  borne   in 


ClRC.  300]  COCCIDIOSIS   OF    CHICKENS  5 

mind  that,  in  many  outbreaks  of  coccidiosis,  this  does  not  occur. 
Therefore,  " bloody  diarrhea,"  the  name  for  the  disease  commonly 
used  by  poultrymen,  does  not  always  apply.  The  use  of  this  name 
should  be  discouraged,  since  it  may  give  poultrymen  the  impression 
that  coccidiosis  is  not  present  in  their  flocks  unless  blood  is  seen  in 
the  droppings. 


Fig.  3.  Seven-months  old  pullet  with  chronic  coccidiosis. 
MORTALITY   GREATEST   AT   START   OF   OUTBREAK 

The  heaviest  mortality  usually  occurs  during  the  first  week  or  ten 
days  after  the  first  droopiness  appears.  After  this,  deaths  become 
less  frequent  but  may  continue  for  from  three  to  four  weeks.  When 
effective  measures  of  control  are  not  adopted,  a  large  percentage  of 
the  survivors  fail  to  develop  normally.  Such  birds  may  never  become 
profitable  and  the  loss  to  the  poultrymen  from  this  source  may  be 
as  great  as  that  resulting  from  mortality. 

OLDER    BIRDS   HAVE   CHRONIC  TYPE   OF   THE    DISEASE 

The  chronic  type  of  the  disease  is  seen  in  older  birds,  usually 
pullets  between  the  ages  of  four  and  eight  months.  It  develops 
slowly  and  may  affect  only  a  few  fowls  in  a  flock.  The  prominent 
symptoms  are  loss  of  appetite,  roughened,  dirty  plumage,  gradual 
loss  of  flesh,  paleness  of  the  comb  and  wattles,  leg  weakness  or  "par- 
alysis" of  the  legs,  or  sluggish,  weak  movements  when  walking.  In 
extreme  cases  of  leg  weakness,  the  fowl  may  lie  on  its  side  with  both 
legs  extended  backward  (fig.  3),  or  it  may  lie  on  its  breast  with  one 


6  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

leg  extended  forward  and  the  other  backward  (fig.  4).  Some  pullets 
that  are  unable  to  stand  appear  quite  normal  in  a  sitting  posture. 
Death  from  chronic  infection  occurs  only  after  several  days  or  even 
weeks  of  sickness.  Chronic  coccidiosis  may  be  easily  confused  with 
the  symptoms  resulting  from  external  parasites,  intestinal  worms  or 
nutritional  disturbances. 


Fig.   4.  Four-months  old  pullet  with   chronic   coccidiosis. 
DISEASE    AFFECTS    CECA    OF    CHICKS 

The  changes  in  the  organs  observed  upon  examination  of  dead 
birds  vary  with  the  duration  of  the  disease  or  the  severity  of  the 
infection.  In  chicks,  the  changes  are  usually  confined  to  the  ceca. 
The  walls  of  these  organs  are,  as  a  rule,  thickened.  The  ceca  may 
be  normal  in  size  or  markedly  distended.  They  often  contain  suffi- 
cient blood  to  give  them  a  reddish  appearance.  In  some  birds,  small, 
whitish  areas  may  be  present  in  the  walls  of  the  ceca.  Such  areas 
are  sometimes  distributed  throughout  the  small  intestine.  The  ceca 
of  chicks  which  linger  for  a  week  or  more  before  death  often  contain 
an  accumulation  of  grayish  or  yellowish -white,  cheesy  material  (fig.  5). 
This  may  consist  of  a  solid  mass  which  appears  to  have  been  deposited 
in  layers  or  it  may  consist  of  a  grayish-white  plug  with  a  hollow  center. 
Frequently  chicks  which  have  died  of  coccidiosis  exhibit  no  definite 
marked  change  in  the  appearance  of  the  ceca  or  of  the  cecal  contents. 
In  such  cases,  the  disease  can  be  recognized  only  by  the  finding  of 
oocysts  on  microscopic  examination  of  the  contents  of  the  ceca. 

Occasionally  the  liver  is  involved.  The  liver  lesions,  when  present, 
consist  of  small,  white  or  yellowish  specks  on  the  surface. 


CIRC.  300]  COCCIDIOSIS   OF    CHICKENS 


CHRONIC    TYPE    AFFECTS    SMALL    INTESTINES 

In  pullets  with  the  chronic  type  of  the  disease,  the  lesions  are  con- 
fined to  the  small  intestines.  The  intestinal  walls  become  thickened 
and  the  lining  has  a  spongy  appearance.  In  severe  cases,  red  blotches 
or  hemorrhagic  areas  may  be  present.  Occasionally  there  is  a  slough- 
ing of  patches  of  the  lining.     The  ceca  rarely  show  any  change. 


Fig.  5.  Ceca  of  chick  with  coccidiosis. 


DISEASE    IN    CHICKS    NOT   ALWAYS    EASY   TO    RECOGNIZE 

Coccidiosis  is  easy  to  recognize  when  affected  chicks  void  bloody 
droppings  or  when  bloody  or  cheesy  material  is  found  in  the  ceca  of 
dead  chicks.  When  these  indications  of  the  disease  are  absent,  it  is 
necessary  to  find  the  parasite  in  the  ceca  in  order  to  definitely  deter- 
mine the  presence  of  coccidiosis.  This  requires  a  microscopic  exami- 
nation. However,  the  disease  is  so  prevalent  that  whenever  droopiness 
or  death  of  a  few  chicks  occurs  in  a  previously  healthy  flock,  the 
presence  of  coccidiosis  should  be  at  once  suspected  and  proper  control 
measures  adopted  without  waiting  for  a  microscopic  examination  to  be 
made.     Chicks  may  then  be  submitted  for  examination  to  a  veteri- 


y  UNIVERSITY    OF    CALIFORNIA EXPERIMENT   STATION 

narian  or  a  laboratory.  The  chicks  will  not  be  injured  by  the  control 
measures  and,  if  coccidiosis  is  found,  they  will  be  benefited  by  receiving 
treatment  so  promptly. 


CHRONIC    TYPE    RESEMBLES    OTHER    DISEASES 

Chronic  coccidiosis  can  be  differentiated  from  the  effects  on  chickens 
of  certain  species  of  intestinal  worms  or  from  some  nutritional  dis- 
turbances only  by  microscopic  examination  of  intestinal  contents 
or  of  scrapings  from  the  lining  of  the  intestines  of  affected  fowls. 
Frequently  both  coccidial  parasites  and  one  or  more  species  of  intes- 
tinal worms  may  be  present  in  the  same  fowl.  Therefore,  before  an 
intelligent  decision  can  be  made  as  to  the  treatment  of  fowls  suspected 
of  having  chronic  coccidiosis,  it  must  be  determined:  first,  whether 
coccidial  parasites  are  present ;  second,  whether  other  intestinal  para- 
sites are  present;  and  third,  whether  there  is  any  relation  between 
nutrition  and  the  condition  of  the  fowls. 


CONTROLLED    BY    DIET    AND    SANITATION 

The  results  of  experiments1  conducted  at  this  station  indicate  that 
feeding  sufficient  buttermilk  or  skim-milk  is  of  considerable  value  in 
controlling  outbreaks  of  coccidiosis.  The  benefit  derived  from  the 
milk  appears  to  be  due  to  two  factors :  first,  its  property  of  producing 
acidity  in  the  ceca,  and,  second,  its  ability  to  stimulate  rapid  growth. 
The  production  of  acidity  is  due  to  the  milk  sugar.  Acidity  can  be 
produced  equally  well  by  feeding  milk  sugar  alone,  sweet  milk,  sour 
milk,  or  dry  skim-milk.  Therefore,  acidity  in  sour  milk,  butter  milk, 
or  other  milk  products  is  not  a  necessary  factor  in  producing  acidity 
in  the  intestinal  tract  of  chickens.  The  same  is  true  of  the  milk- 
souring  bacteria.  Even  the  feeding  of  cultures  of  lactic  acid-producing 
bacteria  adds  nothing  to  the  effectiveness  of  milk.  The  acidity  pro- 
duced in  the  ceca  by  the  milk  sugar  appears  to  be  harmful  to  some 
of  the  forms  of  the  coccidial  parasites  present  in  those  organs.     In 

1  Beach,  J.  E.,  and  Corl,  J.  C.  Studies  in  the  control  of  avian  coccidiosis. 
Poultry  Science  4:  83-93,  1925. 

Beach,  J.  E.  The  effect  of  feeding  lactose,  cultures  of  B.  acidophillus, 
whole  milk  or  dry  skim-milk  on  the  hydrogen  ion  concentration  of  the  cecal 
contents  of  chickens.     Hilgardia  1:   145-166,  1925. 

Beach,  J.  E.,  and  Davis,  D.  E.,  The  influence  of  feeding  lactose  or  dry 
skim-milk  on  artificial  infection  of  chickens  with  sporulated  oocysts  of  Eimeria 
avium.    Hilgardia  1:  167-181,  1925. 


CntC.  300]  COCCIDIOSIS   OF    CHICKENS  9 

order  to  continuously  maintain  acidity  in  the  ceca,  a  more  or  less 
continuous  flow  of  milk  sugar  through  the  intestinal  tract  is  necessary. 
This  has  been  accomplished  by  feeding  mash  containing  20  per  cent 
milk  sugar  or  40  per  cent  dry  skim-milk. 

The  ability  of  milk  to  stimulate  rapid  growth  of  chicks  gives  to 
them  increased  resistance  against  diseases  in  general  and,  therefore, 
against  coccidiosis.  Milk  sugar  alone  is  not  so  suitable  for  use  in 
controlling  coccidiosis  as  dry  skim-milk  or  milk  in  liquid  state,  such  as 
buttermilk,  because  it  is  not  relished  by  the  chicks  and  is  less  nutritious. 

Sanitation  in  the  houses  and  yards  and  the  care  of  the  chicks  are 
as  important  in  the  control  of  the  disease  as  the  use  of  milk  in  the 
ration.  If  these  factors  are  neglected  little  benefit  from  milk  feeding 
can  be  expected. 

Recommendations  concerning  the  use  of  milk  in  the  ration  and  san- 
itary measures  to  control  coccidiosis  follow: 


DRY    SKIM-MILK    IN    MASH 

If  dry  skim-milk  is  used  it  should  constitute  40  per  cent  of  the 
mash.  Since  dry  skim-milk  is  more  expensive  than  the  poultry  feeds 
commonly  used,  this  amount  may  seem  unnecessarily  large ;  however, 
if  less  is  used,  satisfactory  results  cannot  be  expected.  The  dry  skim- 
milk  is  relatively  rich  in  protein,  and,  therefore,  it  should  not  simply 
be  added  to  a  chick  mash  mixture  containing  meat  scrap  or  other 
protein  concentrate ;  instead,  a  special  mixture  should  be  prepared. 
One  that  has  been  found  satisfactory,  both  in  experimental  flocks  and 
in  the  few  cases  where  it  has  been  used  on  poultry  farms,  consists  of 
the  following  ingredients : 

Dry  skim-milk  40  pounds 

Wheat  bran 10  pounds 

Yellow  cornmeal 30  pounds 

Ground  barley  20  pounds 

Start  feeding  the  mash  as  soon  as  the  presence  of  the  disease  is 
determined.  Keep  the  mash  constantly  before  the  chicks  in  hoppers 
or  troughs  constructed  so  as  to  prevent  waste.2 

Provide  sufficient  hoppers  so  that  all  chicks  can  eat  freely.  Fail- 
ure to  do  this  will  result  in  the  weaker  chicks  being  crowded  out  and 


2  Dougherty,  J.  E.,  and   Gossman,  S.   S.     Inexpensive  Labor   Saving  Poultry 
Appliances.     Calif.  Agr.  Exp.  Sta.  Cir.  268:   1-32,  1923. 


10  UNIVERSITY    OF    CALIFORNIA EXPERIMENT   STATION 

not  getting  sufficient  mash.  Determine  the  weight  of  the  mash  con- 
sumed each  day.3 

Feed  grain  once  or  twice  daily  but  restrict  the  amount  to  from 
one-third  to  one-half  the  weight  of  mash  consumed.  If  more  grain 
is  fed,  mash  consumption  will  be  reduced  and  less  satisfactory  results 
will  be  obtained. 

Continue  this  system  of  mash  and  grain  feeding  as  long  as  there 
is  any  indication  of  the  disease.  This  usually  requires  from  one  to 
two  weeks.  If  desired,  the  ration  can  then  be  very  gradually  changed 
to  the  one  in  use  before  coccidiosis  started.  Do  not  start  the  change 
in  the  ration  too  soon  nor  make  it  too  abruptly. 

Feed  greens  as  usual.  If  the  supply  of  greens  is  insufficient,  add 
one  quart  of  cod  liver  oil  to  each  one  hundred  pounds  of  mash.  This 
is  also  advisable  when  weather  conditions  or  weakness  of  chicks  pre- 
vents them  from  running  outside. 

Do  not  neglect  sanitation.     See  p.  12. 

In  our  experimental  work,  as  previously  stated,  it  was  found  that 
this  method  of  feeding  was  suitable  for  use  for  the  short  periods  the 
experiments  were  in  progress.  A  few  poultrymen  have  followed  this 
feeding  program  from  the  time  the  chicks  were  placed  in  the  brooder 
house  until  they  were  two  months  of  age.  They  report  that  the  chicks 
made  rapid  growth  and  matured  early,  and  that  the  percentage  of 
culls  and  the  mortality  were  unusually  low.  The  brooder  yards  used 
were  contaminated  with  the  coccidiosis  germs  (oocysts)  and  a  few 
deposits  of  bloody  droppings  were  observed  at  times  during  the  brood- 
ing period,  showing  that  some  had  become  infected.  However,  there 
were  no  other  indications  of  coccidiosis,  such  as  droopiness,  and  none 
died  from  this  disease. 

Although  the  continuous  use  of  this  feeding  method  may  be  highly 
effective  in  preventing  coccidiosis,  the  high  percentage  of  milk  protein 
in  the  ration  may  result  in  such  unnaturally  rapid  growth  that  the 
chicks  will  suffer  a  setback  when  the  ration  is  changed  to  the  usual 
grain  mixture.  Until  further  information  on  this  point  is  available, 
we  cannot  recommend  that  mash  containing  40  per  cent  dry  skim- 
milk  be  fed  longer  than  three  or  four  weeks. 


3  The  weight  of  mash  consumed  can  be  determined  by  weighing  the  amount 
of  mash  supplied  in  the  morning  and  weighing  back  the  unconsumed  portion 
on  the  following  morning.  The  difference  in  the  weights  represents  the  amount 
consumed  during  the  twenty-four  hour  period.  This  weight  is  used  to  deter- 
mine the  amount  of  grain  to  feed. 


ClRC.  300]  COCCIDIOSIS   OF    CHICKENS  11 


BUTTERMILK   AS   A    DRINK 

When  liquid  milk,  such  as  buttermilk  or  skim-milk,  is  to  be  used, 
first  locate  an  adequate  supply  of  good  quality. 

Keep  the  milk  constantly  before  the  chicks  in  fountains  or  troughs. 
If  troughs  are  used,  provide  covers  that  will  prevent  the  chicks  from 
walking  in  them  or  roosting  over  them.  Provide  sufficient  containers 
so  that  all  the  chicks  can  drink  freely  and  the  weaker  chicks  will  not 
be  crowded  away. 

Allow  the  chicks  no  water. 

Feed  no  mash. 

Feed  grain  twice  daily,  very  sparingly  in  the  morning  and  a  larger 
amount  at  night. 

Feed  greens  as  usual.  Add  one  quart  of  cod  liver  oil  to  each  one 
hundred  pounds  of  mash  if  the  supply  of  greens  is  insufficient  or  the 
chicks  cannot  go  out  of  doors. 

After  all  evidence  of  the  disease  has  disappeared,  the  feeding  of 
mash  may  be  very  gradually  resumed,  water  again  given,  and  the 
amount  of  milk  reduced.  Do  not  start  this  change  in  feeding  too  soon 
nor  complete  it  too  rapidly. 

Do  not  neglect  sanitation.     See  p.  12. 

A  condensed  milk  product,  such  as  semi-solid  buttermilk,  may 
be  used  after  dilution  in  the  same  manner  as  buttermilk.  Use  one 
part  to  two  or  three  parts  of  water.  Greater  dilutions  are  less  bene- 
ficial. Many  poultrymen  report  satisfactory  results  from  the  use  of 
undiluted  semi-solid  buttermilk.  If  it  is  fed  in  this  way,  water  must 
be  supplied. 

MILK    FEEDING    CAUSES    WATERY    DROPPINGS 

When  chicks  are  fed  liberally  with  milk,  either  dry  or  liquid,  the 
droppings  become  watery  and  are  voided  frequently.  This,  in  itself, 
is  not  harmful.  The  watery  consistency  of  the  droppings,  however, 
causes  the  litter  and  floor  to  become  wet  in  a  short  time.  This  makes 
it  necessary  to  clean  out  the  houses  and  renew  the  litter  daily  in  order 
to  keep  the  floor  dry.  When  this  is  not  done,  the  floor  becomes  wet. 
A  condition  is  thus  created  that  is  extremely  favorable  for  the  devel- 
opment of  oocysts  from  the  harmless  to  the  harmful  stage  and  one 
very  unfavorable  for  the  continued  good  health  of  chicks.  This  is  the 
only  way  the  discharge  of  watery  droppings,  resulting  from  milk 
feeding,  may  prove  harmful. 


12  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

ADVANTAGES   OF    DRY   SKIM-MILK 

As  previously  indicated,  the  form  of  milk  used  in  the  control  of 
coccidiosis  is  not  of  great  importance  as  long  as  a  sufficient  quantity  is 
consumed  by  the  chicks.  Dry  skim-milk,  however,  possesses  advan- 
tages which  make  it  somewhat  more  desirable  for  general  use.  Some  of 
these  are  as  follows: 

It  is  the  most  condensed  form  of  milk.  Therefore,  it  is  easier  to 
transport  and  a  sufficient  quantity  may  be  more  easily  consumed.  A 
good  grade  of  dry  skim-milk  contains  about  2.5  per  cent  of  water, 
semi-solid  buttermilk  from  60  to  70  per  cent  of  water,  and  buttermilk 
about  91  per  cent  of  water. 

It  is  easier  to  feed  than  a  liquid  milk. 

It  is  relished  by  chicks.     Buttermilk  is  sometimes  unpalatable. 

It  keeps  well  if  stored  in  tight  containers.  Therefore,  a  quantity 
sufficient  to  last  for  several  weeks  may  be  obtained  at  one  time  and 
daily  trips  to  a  creamery  avoide'd.  This  quality  also  makes  milk 
available  in  localities  distant  from  dairying  districts. 

It  promotes  rapid  development  of  chicks. 

It  provides  a  practical  means  of  feeding  chicks  during  the  period 
of  greatest  danger  from  coccidiosis  (from  four  to  eight  weeks  of  age), 
so  that  they  are  less  liable  to  become  fatally  infected  when  they  are 
run  on  contaminated  soil. 


SANITATION    AND    CARE    ESSENTIAL    TO    CONTROL 

The  sanitary  measures  recommended  are  designed  to  prevent  the 
spread  of  the  germs  from  the  diseased  chicks  to  those  that  are  either 
not  infected  or,  if  infected,  have  not  acquired  a  sufficient  number  of 
the  germs  to  become  visibly  sick.  The  points  regarding  care  are 
intended  to  provide  conditions  favorable  to  maintaining  good  health 
so  that  the  natural  resistance  of  the  chicks  to  disease  will  not  be 
lowered. 

When  coccidiosis  appears: 

Thoroughly  clean  the  brooder  houses  or  move  the  chicks  to  other 
brooders  that  have  been  cleaned  and  disinfected.  Cover  the  floor 
with  litter.  Clean  the  houses  and  put  in  fresh  litter  daily.  By  this 
procedure  a  large  percentage  of  the  oocysts  that  are  present  in  the 
fresh  droppings  of  infected  chicks  are  removed  from  the  houses  before 
sporulation  has  taken  place  and  they  have  become  capable  of  producing 
disease  in  healthy  chicks  (see  fig.  1,  A  and  B).  The  daily  cleaning  is 
also  necessary  to  keep  the  floor  dry.     This  is  of  great  importance 


ClRC  300]  COCCIDIOSIS   OF    CHICKENS  13 

because  dryness  inhibits  sporulation  of  the  oocysts  and  is  essential 
for  the  health  of  the  chicks. 

Divide  the  chicks  into  as  many  flocks  as  the  number  of  brooders 
available  will  permit.  When  the  flocks  are  small,  it  is  easier  to  keep 
the  houses  clean  and  dry  and,  therefore,  outbreaks  of  coccidiosis  can 
be  more  quickly  brought  under  control. 

Be  sure  that  the  brooder  houses  are  kept  warm  enough  and  are 
well  ventilated.  Warmth  and  fresh  air  are  essential  for  the  health 
of  the  chicks  and  also  assist  in  keeping  the  houses  dry. 

Separate  the  visibly  sick  chicks  from  those  apparently  healthy 
as  soon  as  the  disease  appears.  Kill  the  worst  cases.  Burn  the  dead. 
Watch  the  healthy  chicks  carefully  so  that  those  that  later  become 
sick  can  be  promptly  detected  and  removed.  By  this  means,  the 
exposure  of  the  healthy  chicks  to  the  coccidiosis  germs  will  be  lessened, 
and  the  sick  will  be  afforded  a  better  opportunity  to  partake  of  food 
and  their  chances  for  recovery  increased. 

Clean  and  plough  or  spade  the  yards.  Contamination  of  the  soil 
with  coccidiosis  germs  is  greatest  in  that  part  of  the  yards  adjacent 
to  the  houses  where  the  cjiicks  spend  most  of  their  time  when  outside. 
The  surface  of  this  part  of  the  yard  should  be  scraped  or  swept  and  the 
sweepings  removed.  The  entire  yard  should  be  ploughed  as  deeply 
as  possible.  Corners  and  other  places  that  cannot  be  reached  by  the 
plough  should  be  spaded. 

MEDICINES    ARE    OF    LITTLE   VALUE 

Carefully  controlled  experimental  trials  have  been  made  at  this 
station  to  determine  the  value  of  the  drugs  that  have  been  most 
frequently  used  by  poultrymen  in  their  efforts  to  combat  coccidiosis. 
The  drugs  that  were  tried  are  hydrochloric  acid,  catechu,  a  mixture 
of  bichloride  of  mercury  and  sulphocarbolates  (coccidiosis  powder), 
potassium  dichromate,  powdered  ipecac,  and  bismuth  subnitrate. 
None  of  these  were  found  to  be  effective. 

SOME    CAUSES   OF    FAILURE   TO    CONTROL  THE    DISEASE 

The  successf  ill  control  of  outbreaks  of  coccidiosis  by  the  previously 
described  methods  depends  upon  careful  attention  to  all  the  details. 
Below  are  listed  some  of  the  mistakes  or  omissions  that,  if  made,  might 
result  in  failure : 

1.  Feeding  too  much  grain  with  either  dry  or  liquid  milk. 

2.  Continuing  to  feed  mash  with  liquid  milk. 

3.  Continuing  to  give  water  with  liquid  milk. 


14  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

4.  Diluting  condensed  milk    (semi-solid)    too   much. 

5.  Discontinuing  the  milk  feeding  too  soon. 

6.  Feeding  unpalatable   (bitter)   buttermilk  or  semi-solid  buttermilk.     The 

chicks  fail  to  consume  enough. 

7.  Feeding  buttermilk  containing  too  much  water   (churn  washings). 

8.  Having  too  few  mash  hoppers  or  milk  containers.     The  weaker  chicks 

are  crowded  out. 

9.  Keeping  too  many  chicks  in  a  house.     The  chicks  suffer  from  crowding. 

10.  Delaying  the  start  of  treatment  until  a  large  part  of  the  flock  is  affected. 

11.  Failing  to  recognize  the  presence  of  other  intestinal  parasites,  such  as 

intestinal  round  worms. 

12.  Neglecting  to  clean  houses   (most  commmon  omission). 

SANITATION    PREVENTS    DISEASE 

Infection  with  coccidiosis  can  be  prevented  by  raising  chicks  in 
houses  and  on  soil  that  are  free  from  contamination  with  the  causative 
organism.  Houses  can  be  made  safe  by  thorough  cleaning  and  disin- 
fection of  the  floors,  sidewalls,  hovers,  mash  hoppers,  drinking  foun- 
tains, and  all  other  appliances  before  the  chicks  are  placed  in  them. 
A  house  cannot  be  regarded  as  thoroughly  cleaned  until  all  of  the 
droppings  that  have  become  dried  onto  the  floor,  hover,  etc.,  are 
scraped  or  scrubbed  loose.  Cleaning  is  facilitated  by  the  use  of  a  hot 
lye  solution  (one  pound  lye  to  forty  gallons  of  water).  Oocysts  are 
destroyed  by  sufficient  exposure  to  a  5  per  cent  solution  of  compound 
solution  of  cresol.  It  is,  therefore,  a  suitable  disinfectant  for  use  in 
brooder  houses.  The  house  should  be  kept  clean  and  dry  throughout 
the  brooding  period. 

Soil  that  has  not  previously  been  used  for  chickens  and  that  has 
not  been  fertilized  with  poultry  manure  may  be  regarded  as  safe. 
Soil  that  has  become  contaminated  can  be  made  comparatively  safe 
by  excluding  poultry  from  it  for  at  least  a  year,  during  which  time 
it  is  cultivated  so  as  to  dry  the  top  layer  as  much  as  possible.  Since 
the  germ  is  quite  susceptible  to  dryness,  the  greater  the  degree  and 
depth  of  the  dryness  of  the  soil  that  is  obtained,  the  more  effective 
the  treatment.  Merely  plowing  and  cropping  for  a  season  will  not 
suffice.  There  is  no  practical  method  of  chemical  treatment  of  soil 
to  assist  in  eradicating  contamination.  Soil  that  is  used  for  chicks 
each  year  is  almost  certain  to  be  continuously  contaminated.  This 
is  true  even  though  but  a  single  lot  of  chicks  is  reared  on  it  each  year 
and  all  poultry  are  excluded  from  it  during  the  remainder  of  the  time. 
This  practice,  however,  is  much  less  dangerous  than  raising  two  or 
more  lots  of  chicks  in  the  same  yards  during  the  year.  It  is  the 
common  experience  of  poultry  men  who  follow  the  latter  practice 


ClRC  300]  COCCIDIOSIS   OF    CHICKENS  15 

to  suffer  increasingly  greater  losses  from  coccidiosis  in  each  successive 
lot  of  chicks  brooded  during  any  one  year.  Providing  sufficient 
brooder  yards  so  that  each  one  need  be  used  only  every  other  year 
would  undoubtedly  accomplish  much  toward  eliminating  losses  from 
coccidiosis. 

An  alternate  method  that  may  be  used  on  poultry  farms  on  which 
the  area  available  for  brooder  yards  is  too  limited  to  permit  more  than 
one  yard  for  each  brooder  house  is  to  reduce  the  size  of  the  yards  so 
that  they  may  be  floored  with  concrete  at  a  reasonable  cost.  This 
plan  was  successfully  used  during  the  1925  brooding  season  by  the 
Division  of  Poultry  Husbandry  at  the  University  Farm,  Davis,  Cali- 
fornia. 

The  soil  of  orchard  or  garden  land  that  has  been  fertilized  with 
poultry  manure  is  liable  to  contain  oocysts  and,  therefore,  is  not  suit- 
able for  chicks. 

Moist  soil  around  outside  watering  places  is  a  very  favorable  place 
for  the  parasites  to  sporulate  and  may  readily  become  a  serious  source 
of  infection  in  yards  that  are  otherwise  clean.  To  avoid  this,  remove 
the  dirt  to  a  depth  of  about  two  feet  from  the  area  around  the  watering 
vessels  that  becomes  moistened  by  overflow  or  by  the  water  that  drops 
or  is  thrown  off  the  beaks  of  the  birds  when  they  drink.  Replace  the 
dirt  with  coarse  gravel ;  cover  this  with  a  slat  platform,  and  place  the 
watering  vessels  in  the  center  of  the  platform.  This  arrangement  is 
also  of  value  in  the  prevention  of  infection  by  other  forms  of  intestinal 
parasites. 

INFECTION   MAY  BE   CARRIED  TO   NEW  PREMISES 

Poultrymen  on  new  premises  should  avoid  as  much  as  possible 
contamination  of  the  soil  of  brooder  yards  by  mature  stock  that  may 
harbor  the  infection,  or  by  wild  birds,  dust-laden  wind,  streams, 
visitors,  dogs,  cats  or  other  animals  that  may  serve  as  mechanical 
carriers  of  the  germs. 

There  is  no  other  apparent  explanation  of  the  source  of  the  infection 
responsible  for  some  outbreaks  that  occur  in  the  first  brood  of  chicks 
raised  on  new  premises,  Usually,  however,  infection  introduced  by 
these  means  does  not  result  in  immediate  serious  losses. 


25m-12,'25 


